Table 3 Results of tephra analysis for T1 and T6
Tephra layer | Volcanic glass shards refractive index | Number of volcanic glass shards measured | Volcanic glass morphology | Orthopyroxene shards refractive index | Number of orthopyroxene shards measured | Remarks | Correlative tephra | ||
|---|---|---|---|---|---|---|---|---|---|
Range | Mode | Range | Mode | ||||||
Results of tephra analysis for T1 and T6 | Â | Â | Â | Â | Â | Â | Â | Â | Â |
T1 | 1.4933–1.4990 1.5023–1.5051 1.5055–1.5083 1.5088–1.5146 1.5227–1.5227 | – 1.504 1.507 – – | 4 9 55 12 1 | C, T, H, It T, C, H, It T, C, H > It T, C T | 1.699–1.712 1.714–1716 1.721–1.722 | 1.707–1.708 1.715 – | 46 11 3 | Heavy minerals: Opx (Hypersthene > Bronzite) (γ = 1.699–1.722), Opq, Cpx > GHb Light minerals: Pl, Qz | Towada-a (To-a) |
T6 | 1.5008–1.5112 1.5116–1.5148 | – 1.513 | 16 60 | T, C, H, It T > C | 1.699–1.703 1.704–1.709 1.711–1.712 | – 1.707 – | 4 54 2 | Heavy minerals: Opx (Hypersthene) (γ = 1.707), Opq, Cpx > Ap Light minerals: Pl, Qz | Towada-Chuseri (To-Cu) |
Reference values (Machida and Arai 2003) | Â | Â | Â | Â | Â | Â | Â | Â | Â |
To-a | 1.496–1.508 (1.502–1.506) | – | – | – | – | – | – | Opx: 1.706–1.708 (1.707) | – |
To-Cu | 1.510–1.514 (1.511–1.513) | – | – | – | – | – | – | Opx: 1.704–1.708 (1.707) | – |